It is known that discotic liquid-crystalline compounds are extremely important compounds as a material for optically-compensatory sheets. As a liquid-crystalline compound that expresses discotic liquid-crystallinity, disclosed is 2,3,6,7,10,11-hexa{4-(4-acryloyloxyhexyloxy)benzoyloxy}triphenylene (JP-A 7-306317).
The retardation (Δnd) of an optically-compensatory sheet is determined depending on the optical properties of the liquid-crystal cell to be compensated with the sheet. Retardation (Δnd) is a product of the refractivity anisotropy (Δn) of an optically-anisotropic layer and the thickness (d) of the optically-anisotropic layer. When the refractivity anisotropy (Δn) of an optically-anisotropic layer is large, then the layer may be effective for compensating a liquid-crystal cell even though the thickness (d) of the layer is thin. On the contrary, when the refractivity anisotropy (Δn) thereof is small, then the thickness (d) of the layer must be large, and, as a result, it may be problematic in that there may readily occur defects in the alignment of liquid-crystalline compounds. Compounds having a high Δn are desired.
A compound having a molecular structure similar to that of the liquid-crystalline compound of the invention is reported in Molecular Crystals and Liquid Crystals, 2001, Vol. 370, p. 391 (JD-2; see Comparative Example 2). However, it has been found that the skeleton could not readily attain a lower wavelength dispersibility than 2,3,6,7,10,11-hexa{4-(alkyloxybenzoyloxy}triphenylene, as described in Examples given hereinunder.